In my opinion: nowhere… Only the miserable, expensive original Velleman pulley’s are for sale.
This pulley’s (picture) are GT2 20 and I am glad I did this hack some time ago. Never had any problems since then.

[quote=“svdv”]In my opinion: nowhere… Only the miserable, expensive original Velleman pulley’s are for sale.
This pulley’s (picture) are GT2 20 and I am glad I did this hack some time ago. Never had any problems since then.[/quote]

Thanks for your reply, I really appreciate…

And where can I buy this GT2 20T (Pitch: 2mm or Pitch: 2.5mm) ?
And can you keep using the original belts?
And what settings do you need to change to print in the right size with these pulleys?

Can I also post in Dutch here ?
because that makes it a lot easier for me

[quote]And where can I buy this GT2 20T (Pitch: 2mm or Pitch: 2.5mm) ?
And can you keep using the original belts?
And what settings do you need to change to print in the right size with these pulleys?
Can I also post in Dutch here ? [/quote]
I bought the whole set in France, see this https://www.dropbox.com/s/b3ogpf5esyd1vwt/facture-imp3d.pdf?dl=0.
You can’t keep the original belts, it’s 20 teeth, and the long belts are open.
The instruction with all details (from Logmett) can be found here: thingiverse.com/thing:1857266
This is an English forum so everyone can learn something from each other.

Just get an email that I found a company that can make the pulleys looks like the GT2-20, but in size T2.5 - 19 Tooth - 8mm drill - 2x M4 grubscrew holes. Now the question is what they are going to cost (I’m waiting for reply).
When this becomes too expensive, I’m going to look for the GT2-20 because the original pulleys are really bad, I do not understand that Velleman have chosen for this pulleys…

Edite: Unfortunately, that is getting too expensive, this is the manufacturer’s response: